Flash lamp and method of



M. PxPKlN Re 22,838

FLI'SH LAMP AND METHOD OF MNUFACTURE THEREOF Feb. 4, 1947.

original Filed Dec.- 31, i941 Marvm Plpkm,

H15 AtftoT-Tweg Reissued Feb. 4, 1947 UNITED STATES PATENT OFFICE New York @riginal No. 2,383,076, dated August 21, 1945, Serial No. 425,014, December 31, 1941. Application for reissue April 6, 1946, Serial No. 660,052

( Cl. lli- 59) 6 Claims.

My invention relates in general to liash lamps or similar devices comprising a sealed enclosure, and to a method of manufacturing the same. More particularly, my invention relates to the construction of the enclosure for such flash lamps and similar devices.

In flash lamps in general use at present, the enclosing bulb for the light-producing charge is usually made of glass or other vitreous material. Obviously, with such ash lamps there is always the danger of fiying fragments of broken glass when the lamp, for some unexpected reason, explodes on charge hashing.

One object of my invention is to provide a flash lamp having a bulb made of a material such that the bulb will not break and shatter, so as to scatter ying fragments of the bulb, in the event an explosion should occur upon flashing of the lamp.

Another object of my invention is to provide a method of manufacturing such a substantially nonbreakable and nonshatterable flash lamp.

Still another object of my invention is to provide a flash lamp having a bulb made of a relatively inexpensive material of such a nature that broken fragments thereof will not possess any sharp cutting surfaces such as are apt to produce bodily injury.

A feature of my invention is the use of a bulb made of a suitable plastic material and sealed to the glass stem of the lamp mount structure.

Further objects and advantages of my invention will appear from the following description of species thereof and from the accompanying drawing in which:

Fig. 1 is an elevation of a flash lamp comprising my invention; Figs. 2, 3 and 4 are views illustrating the steps involved in manufacturing the flash lamp shown in Fig. l; Fig. 5 is a fragmentary sectional view, on an enlarged scale, showing the completed seal between the bulb and stem of the lamp shown in Figs. 1-4; Fig. 6 is an elevation of a modified form of ash lamp comprising my invention; and Fig. 7 is a view illustrating one of the steps involved in manufacturing the modied form of flash lamp shown in Fig. 6.

In the drawing, Figs. 1 4 illustrate the invention as applied to a flash lamp of the type disclosed and claimed in my copending application Serial No. 328,399, led April 3, 1940, now Patent No. 2,291,983, in which the source of actinic radiation is constituted by one or more beads or compact masses of an agglutinated flashlight powder admixture disposed within the lamp bulb and comprising a combustible metallic powder such as zirconium or magnesium or mixtures.

thereof, and a supporter of combustion consisting 0f oxygen-evolving powder such as calcium peroxide, potassium perchlorate, etc.

Referring to Figs. 1 4, the flash lamp there shown comprises a bulb or envelope Il] of a suitable plastic material capable of transmitting radiations produced within the bulb by the lightgenerating means disposed therein and hereinafter described. The plastic material employed for the bulb may be any of the Well-known plastic materials, such as cellulose acetate, which possess the property of becoming soft either when immersed in a suitable solvent or when heated; i. e., thermoplastic. The bulb ID, if desired, may be coated on its outside and/or inside surface (preferably the inside) with a suitable lacquer or similar material.

The bulb i0 is formed with a neck II to which the glass stem I 3 of a lamp mount structure I2 is sealed. The mount structure I2 comprises, in addition to the stem I3, a pair of leading-in wires I4, I6.. sealed into the press portion I5 of the glass stem and provided with juxtapositioned inner lead portions I", I5. Extending between the inner lead portions I9, Iii andelectrically connected thereto is an ignition iilament I1 of a suitable refractory metal, such as tungsten. Disposed on the tip of each inner lead I6 is a small f first formed separately, as shown in Fig. 2, and

then attached and sealed together to form the complete bulb assembly. The attachment and sealing of the glass stem I3 to the bulb neck II is efiected, according to the invention, ,by first softening the neck of the bulb so that it becomes pliable and somewhat tacky, and then rolling or pressing the softened Wall of the bulb neck around the periphery of a flange 20 formed on the stem I3 at the outer end thereof.

Referring to Fig. 3, showing one manner of sealing the bulb and the mount structure together, the flanged end of the stem I3 and the neck end of the bulb are placed in a suitably shaped cup or container 2| in proper assembled interrelation, with the bulb neck surrounding the flange 25). The container 2l is lled with a suitable solvent 22 capable of softening the plastic material of which the bulb I0 is made. Where cellulose acetate is used as the material for the bulb Ill, the solvent 22 may consist of, for instance, acetone. As the bulb neck gradually softens and acquires a tacky condition, it tends to shrink down onto and adhere to the rim or peripheral edge of the flange 20 on the stem. The so attached bulb and mount structure are eases then removed from the container 2| and the bulb neck, while still in a soft and pliable state, pressed against and molded around the rim or peripheral edge of the stern flange 20 by means of one or more suitable shaping tools or rollers 23 (Fig. 4) to thereby adhesively attach and seal the bulb neck to the stem flange. To better insure a hermetic seal, and also to strengthen the same, it may be desirable to apply a coating 24 of a suitable lacquer or similar material around the seal, as shown in Fig. 5.-

After the mount I2 has been sealed into the bulb, the base I9 is cemented or otherwise secured to the bulb neck and the leading-in wires I4, I4 suitably connected to the terminals of the base,` as bysoldering, thus completing the flash lamp.

Instead of placing both the bulb I and the mount structure I2 in assembled relation in the solvent 22, the bulb alone may be immersed in the solvent and after the neck becomes soft, the bulb removed from the solvent, the mount I2 inserted in place within the bulb, and the bulb neck, while still soft and pliable, then pressed into engagement with the rim or peripheral edge of the stem flange 20, as before. With this method, however, it is necessary that the bulb neck be made of such an internal diameter that, after the softening and shrinkage of the bulb neck, the internal diameter thereof will still be sufficient to permit entry of the stem flange 20 thereinto.

Where the plastic material used for the bulb Iii possesses the property of becoming soft upon the application of heat thereto, then the soften'- ing of the bulb neck II may be eiected instead by heating the same in a suitable manner, as

by conduction from a heating element in contact f with the bulb neck. After the bulb neck has been thus softened, the lamp mount structure I2 is inserted in place within the bulb and the stem I3 attached and sealed to the softened neck by pressing the latter down onto the peripheral edge of the stem ilangeZIl, as before,

Figs. 6J? illustrate the invention as applied to a flash lamp of the type in which a quantity of readily ignitable metal, in the form of a thin foil or in iilamentary form, is loosely disposed throughout the lamp bulb. Except .for the presence oi the loosely distributed combustible material 25, the lamp shown in Figs. 6 and 7 otherwise is substantially the same as that shown in Fig. l, The combustible material 25 preferably consists of aluminum or magnesium, or alloys thereof, in filamentary form.

The manufacture of the lamp shown in Fig. 6 is substantially the same as that disclosed hereinabove in connection with Figs. 1 and 5, the only difference being that the bulb Ill is first lled with the combustible material 25, as shown in Fig. 7, before the mount structure I2 is sealed thereinto. After the bulb I0 has been so illled with the combustible material 25, the mount structure I2 is then sealed into the bulb by any of the methods disclosed hereinabove in connection with Figs. 1 to 4.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In the manufacture of a lamp comprising a bulb of organic plastic material and a mount structure comprising a flanged stem tube having an exhaust tube depending therefrom, the steps which comprise assembling the mount and bulb with the stem tube telescoped in the bulb neck and with the lower end of the bulb neck and the adjoining stem flange located in an annular trough-shaped container containing a solvent for the material of the bulb and with the exhaust tube extending through the central opening in the annular trough, whereby the bulb neck is softened by the solvent and shrunk around the stem ange, removing the assemblyfrom the trough, and then pressing the softened neck portion into firm engagement with the stem iiange.

2. A ash lamp of the type comprising a bulb having a compact body of agglutinated material supported therein and comprising a combustible and a supporter of combustion intimately associated with each other, and electrical means at least a portion of which is in contact with said body for developing an ignition temperature therein, said body constituting the sole source of radiation emitted by the lampk wherein the said bulb consists of light-transmitting organic plastic material.

3. A flash lamp of the type comprising a hollow bulb having supported therein agglutinated material comprising a combustible and a supporter of combustion which constitutes the light-giving material wherein the said bulb consists of lighttransmitting organic plastic material.

4. A ash lamp of the type comprising a hollow bulb having supported therein a ilash charge comprising nely divided combustible material in a concentrated mass carrying its own solid oxygen-evolving agent and constituting substantially the sole source of radiation emitted by the lamp, and ignition means for developing an ignition temperature in said flash charge, wherein the said bulb consists of light-transmitting organic plastic material.

5. A flash lamp of the type comprising a hollowv bulb having a compact charge of agglutinated material supported therein and comprising aY associated with each other and coated on saidV conductors in position to be ignited upon heating of said filament to emit a iiash of light constituting substantially the sole source oi radiation emitted by the lamp, wherein the said bulb consists of light-transmitting organic plastic material.

MARVIN PIPKIN.

REFERENCES CITED The following references are of record in th le of this patent:

UNITED STATES PATENTS Number Name l Date 2,272,059 De Margitta Feb. 3, 1942 2,333,725 Kreidler Nov. 9, 1943 FOREIGN PATENTS Number Country Date Germany May 25, 1932 

